[PATCH v5 06/22] block/xen-blkfront: Split blkif_queue_request in 2
Julien Grall
julien.grall at citrix.com
Wed Sep 30 03:45:21 PDT 2015
Currently, blkif_queue_request has 2 distinct execution path:
- Send a discard request
- Send a read/write request
The function is also allocating grants to use for generating the
request. Although, this is only used for read/write request.
Rather than having a function with 2 distinct execution path, separate
the function in 2. This will also remove one level of tabulation.
Signed-off-by: Julien Grall <julien.grall at citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau at citrix.com>
---
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Cc: David Vrabel <david.vrabel at citrix.com>
Roger, if you really want if can drop the else clause in
blkif_queue_request, IHMO it's more clear here. Although I've kept
your Reviewed-by. Let me know if it's not fine.
Changes in v3:
- Fix errors reported by checkpatch.pl
- Add Roger's Reviewed-by
Changes in v2:
- Patch added
---
drivers/block/xen-blkfront.c | 277 ++++++++++++++++++++++++-------------------
1 file changed, 153 insertions(+), 124 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 0823a96..c94ca26 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -394,13 +394,35 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
return 0;
}
-/*
- * Generate a Xen blkfront IO request from a blk layer request. Reads
- * and writes are handled as expected.
- *
- * @req: a request struct
- */
-static int blkif_queue_request(struct request *req)
+static int blkif_queue_discard_req(struct request *req)
+{
+ struct blkfront_info *info = req->rq_disk->private_data;
+ struct blkif_request *ring_req;
+ unsigned long id;
+
+ /* Fill out a communications ring structure. */
+ ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
+ id = get_id_from_freelist(info);
+ info->shadow[id].request = req;
+
+ ring_req->operation = BLKIF_OP_DISCARD;
+ ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
+ ring_req->u.discard.id = id;
+ ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
+ if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
+ ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
+ else
+ ring_req->u.discard.flag = 0;
+
+ info->ring.req_prod_pvt++;
+
+ /* Keep a private copy so we can reissue requests when recovering. */
+ info->shadow[id].req = *ring_req;
+
+ return 0;
+}
+
+static int blkif_queue_rw_req(struct request *req)
{
struct blkfront_info *info = req->rq_disk->private_data;
struct blkif_request *ring_req;
@@ -420,9 +442,6 @@ static int blkif_queue_request(struct request *req)
struct scatterlist *sg;
int nseg, max_grefs;
- if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
- return 1;
-
max_grefs = req->nr_phys_segments;
if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
/*
@@ -452,139 +471,131 @@ static int blkif_queue_request(struct request *req)
id = get_id_from_freelist(info);
info->shadow[id].request = req;
- if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
- ring_req->operation = BLKIF_OP_DISCARD;
- ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
- ring_req->u.discard.id = id;
- ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
- if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
- ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
- else
- ring_req->u.discard.flag = 0;
+ BUG_ON(info->max_indirect_segments == 0 &&
+ req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
+ BUG_ON(info->max_indirect_segments &&
+ req->nr_phys_segments > info->max_indirect_segments);
+ nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
+ ring_req->u.rw.id = id;
+ if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
+ /*
+ * The indirect operation can only be a BLKIF_OP_READ or
+ * BLKIF_OP_WRITE
+ */
+ BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
+ ring_req->operation = BLKIF_OP_INDIRECT;
+ ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
+ BLKIF_OP_WRITE : BLKIF_OP_READ;
+ ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
+ ring_req->u.indirect.handle = info->handle;
+ ring_req->u.indirect.nr_segments = nseg;
} else {
- BUG_ON(info->max_indirect_segments == 0 &&
- req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
- BUG_ON(info->max_indirect_segments &&
- req->nr_phys_segments > info->max_indirect_segments);
- nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
- ring_req->u.rw.id = id;
- if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
+ ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
+ ring_req->u.rw.handle = info->handle;
+ ring_req->operation = rq_data_dir(req) ?
+ BLKIF_OP_WRITE : BLKIF_OP_READ;
+ if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
/*
- * The indirect operation can only be a BLKIF_OP_READ or
- * BLKIF_OP_WRITE
+ * Ideally we can do an unordered flush-to-disk.
+ * In case the backend onlysupports barriers, use that.
+ * A barrier request a superset of FUA, so we can
+ * implement it the same way. (It's also a FLUSH+FUA,
+ * since it is guaranteed ordered WRT previous writes.)
*/
- BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
- ring_req->operation = BLKIF_OP_INDIRECT;
- ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
- BLKIF_OP_WRITE : BLKIF_OP_READ;
- ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
- ring_req->u.indirect.handle = info->handle;
- ring_req->u.indirect.nr_segments = nseg;
- } else {
- ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
- ring_req->u.rw.handle = info->handle;
- ring_req->operation = rq_data_dir(req) ?
- BLKIF_OP_WRITE : BLKIF_OP_READ;
- if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
- /*
- * Ideally we can do an unordered flush-to-disk. In case the
- * backend onlysupports barriers, use that. A barrier request
- * a superset of FUA, so we can implement it the same
- * way. (It's also a FLUSH+FUA, since it is
- * guaranteed ordered WRT previous writes.)
- */
- switch (info->feature_flush &
- ((REQ_FLUSH|REQ_FUA))) {
- case REQ_FLUSH|REQ_FUA:
- ring_req->operation =
- BLKIF_OP_WRITE_BARRIER;
- break;
- case REQ_FLUSH:
- ring_req->operation =
- BLKIF_OP_FLUSH_DISKCACHE;
- break;
- default:
- ring_req->operation = 0;
- }
+ switch (info->feature_flush &
+ ((REQ_FLUSH|REQ_FUA))) {
+ case REQ_FLUSH|REQ_FUA:
+ ring_req->operation =
+ BLKIF_OP_WRITE_BARRIER;
+ break;
+ case REQ_FLUSH:
+ ring_req->operation =
+ BLKIF_OP_FLUSH_DISKCACHE;
+ break;
+ default:
+ ring_req->operation = 0;
}
- ring_req->u.rw.nr_segments = nseg;
}
- for_each_sg(info->shadow[id].sg, sg, nseg, i) {
- fsect = sg->offset >> 9;
- lsect = fsect + (sg->length >> 9) - 1;
+ ring_req->u.rw.nr_segments = nseg;
+ }
+ for_each_sg(info->shadow[id].sg, sg, nseg, i) {
+ fsect = sg->offset >> 9;
+ lsect = fsect + (sg->length >> 9) - 1;
- if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
- (i % SEGS_PER_INDIRECT_FRAME == 0)) {
- unsigned long uninitialized_var(pfn);
+ if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
+ (i % SEGS_PER_INDIRECT_FRAME == 0)) {
+ unsigned long uninitialized_var(pfn);
- if (segments)
- kunmap_atomic(segments);
+ if (segments)
+ kunmap_atomic(segments);
- n = i / SEGS_PER_INDIRECT_FRAME;
- if (!info->feature_persistent) {
- struct page *indirect_page;
-
- /* Fetch a pre-allocated page to use for indirect grefs */
- BUG_ON(list_empty(&info->indirect_pages));
- indirect_page = list_first_entry(&info->indirect_pages,
- struct page, lru);
- list_del(&indirect_page->lru);
- pfn = page_to_pfn(indirect_page);
- }
- gnt_list_entry = get_grant(&gref_head, pfn, info);
- info->shadow[id].indirect_grants[n] = gnt_list_entry;
- segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
- ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
+ n = i / SEGS_PER_INDIRECT_FRAME;
+ if (!info->feature_persistent) {
+ struct page *indirect_page;
+
+ /*
+ * Fetch a pre-allocated page to use for
+ * indirect grefs
+ */
+ BUG_ON(list_empty(&info->indirect_pages));
+ indirect_page = list_first_entry(&info->indirect_pages,
+ struct page, lru);
+ list_del(&indirect_page->lru);
+ pfn = page_to_pfn(indirect_page);
}
+ gnt_list_entry = get_grant(&gref_head, pfn, info);
+ info->shadow[id].indirect_grants[n] = gnt_list_entry;
+ segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
+ ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
+ }
- gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
- ref = gnt_list_entry->gref;
+ gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
+ ref = gnt_list_entry->gref;
- info->shadow[id].grants_used[i] = gnt_list_entry;
+ info->shadow[id].grants_used[i] = gnt_list_entry;
- if (rq_data_dir(req) && info->feature_persistent) {
- char *bvec_data;
- void *shared_data;
+ if (rq_data_dir(req) && info->feature_persistent) {
+ char *bvec_data;
+ void *shared_data;
- BUG_ON(sg->offset + sg->length > PAGE_SIZE);
+ BUG_ON(sg->offset + sg->length > PAGE_SIZE);
- shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
- bvec_data = kmap_atomic(sg_page(sg));
+ shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
+ bvec_data = kmap_atomic(sg_page(sg));
- /*
- * this does not wipe data stored outside the
- * range sg->offset..sg->offset+sg->length.
- * Therefore, blkback *could* see data from
- * previous requests. This is OK as long as
- * persistent grants are shared with just one
- * domain. It may need refactoring if this
- * changes
- */
- memcpy(shared_data + sg->offset,
- bvec_data + sg->offset,
- sg->length);
+ /*
+ * this does not wipe data stored outside the
+ * range sg->offset..sg->offset+sg->length.
+ * Therefore, blkback *could* see data from
+ * previous requests. This is OK as long as
+ * persistent grants are shared with just one
+ * domain. It may need refactoring if this
+ * changes
+ */
+ memcpy(shared_data + sg->offset,
+ bvec_data + sg->offset,
+ sg->length);
- kunmap_atomic(bvec_data);
- kunmap_atomic(shared_data);
- }
- if (ring_req->operation != BLKIF_OP_INDIRECT) {
- ring_req->u.rw.seg[i] =
- (struct blkif_request_segment) {
- .gref = ref,
- .first_sect = fsect,
- .last_sect = lsect };
- } else {
- n = i % SEGS_PER_INDIRECT_FRAME;
- segments[n] =
+ kunmap_atomic(bvec_data);
+ kunmap_atomic(shared_data);
+ }
+ if (ring_req->operation != BLKIF_OP_INDIRECT) {
+ ring_req->u.rw.seg[i] =
(struct blkif_request_segment) {
- .gref = ref,
- .first_sect = fsect,
- .last_sect = lsect };
- }
+ .gref = ref,
+ .first_sect = fsect,
+ .last_sect = lsect };
+ } else {
+ n = i % SEGS_PER_INDIRECT_FRAME;
+ segments[n] =
+ (struct blkif_request_segment) {
+ .gref = ref,
+ .first_sect = fsect,
+ .last_sect = lsect };
}
- if (segments)
- kunmap_atomic(segments);
}
+ if (segments)
+ kunmap_atomic(segments);
info->ring.req_prod_pvt++;
@@ -597,6 +608,24 @@ static int blkif_queue_request(struct request *req)
return 0;
}
+/*
+ * Generate a Xen blkfront IO request from a blk layer request. Reads
+ * and writes are handled as expected.
+ *
+ * @req: a request struct
+ */
+static int blkif_queue_request(struct request *req)
+{
+ struct blkfront_info *info = req->rq_disk->private_data;
+
+ if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
+ return 1;
+
+ if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE)))
+ return blkif_queue_discard_req(req);
+ else
+ return blkif_queue_rw_req(req);
+}
static inline void flush_requests(struct blkfront_info *info)
{
--
2.1.4
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